The long-term objective of the present proposal is to improve stuttering treatment, specifically a treatment for adults entitled Modifying Phonation Intervals (MPI), a variant of prolonged speech. The MPI program forces the speaker to alter phonated intervals (PIs) (roughly defined as the time from vocal fold onset to offset) in order to instate fluency; however, the most effective way (for maintained reductions in stuttering) in which the distribution should be altered has not been adequately tested. Therefore, Pis will be measured during several fluency-inducing conditions (FICs) in order to further study the role of Pis in the reduction of stuttering in general and possibly aid in the refinement of the MPI program. The present investigation will be a within- and between-subjects experimental design with each participant completing six different conditions: four FICs (chorus reading, prolonged speech, rhythmic speech, and masking) and two control (reading and monologue). Experimental condition PI distributions will be compared to control condition distributions in order to examine alterations during these important fluency- inducing techniques. Analysis of variance and subsequent t-tests will be used to analyze the data.